Adding a system call from within a module isn't a very good idea. For reasons
on this search the archives on kernel-newbies and linux-kernel. This topic
has been discussed many times.
On Friday 12 July 2002 4:00 pm, Karthik M wrote:
> hi,
>
> I was trying to add a system call from a module. I was
> trying out a sample program to do the same.
>
> It gave me an error when i tried to insert the module
> into the kernel. The error stmt was:
>
> ---snip-----
>
> [root]# insmod testcall.o
> testcall.o: init_module: Device or resource busy
> Hint: insmod errors can be caused by incorrect module
> parameters, including invalid IO or IRQ parameters
> [root]#
>
> ---snip----
>
> The program was :
>
> -----snip-----
>
> #include<linux/kernel.h>
> #include<linux/module.h>
> #include<linux/sys.h>
> #include<sys/syscall.h>
>
> static const char *version = "testcall.c: 7/11/2002
> Karthik";
>
> static int syscall_num = 225;
>
> extern int sys_call_table[];
>
> asmlinkage int sys_hello(void)
> {
> printk("The kernel says 'Hi'\n");
> return 1;
> }
>
> int init_module(void)
> {
> printk(version);
>
> if(sys_call_table[syscall_num])
> {
> printk("Error : %d",syscall_num);
> return 1;
> }
>
> sys_call_table[syscall_num] = (int)sys_hello;
>
> return 0;
>
> }
>
> void cleanup_module(void)
> {
> sys_call_table[syscall_num] = 0;
> }
>
> -----snip-----
>
> The command used to compile was:
>
> ----snip----
>
> [root]# gcc -D__KERNEL__ -DMODULE -Wall
> -I/usr/src/linux/include -O2 -c te
> stcall.c
>
> ----snip----
>
> I am stuck and could'nt find a possible solution for
> this problem.
>
> TIA
>
> karthik
>
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